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Crystallization of alcohol ethoxylate diblock copolymers from body‐centred cubic micellar phases formed in concentrated aqueous solutions
Author(s) -
Hamley I. W.,
Pople J. A.,
Ameri M.,
Attwood D.,
Booth C.,
Ryan A. J.
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19980801)199:8<1753::aid-macp1753>3.0.co;2-o
Subject(s) - crystallization , small angle x ray scattering , lamellar structure , materials science , copolymer , crystallinity , polymer chemistry , aqueous solution , phase (matter) , crystallography , chemical engineering , gyroid , scattering , chemistry , polymer , composite material , organic chemistry , optics , physics , engineering
Crystallization in concentrated aqueous solutions of the alcohol ethoxylate diblock copolymers C 11 E 40 , C 15 E 39 and C 17 E 40 (where C = methylene or methyl and E = oxyethylene) has been investigated using small‐angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering (WAXS) and rheology. It is shown that the gel phase formed in these materials has body‐centred cubic (bcc) symmetry, and that the bcc structure can be macroscopically oriented by large amplitude oscillatory shear. At concentrations above about 55 wt.‐% copolymer, crystallization of the poly(oxyethylene) block occurs at low temperatures, and the effect of crystallization from the oriented bcc structure of a 70 wt.‐% solution is examined using SAXS/WAXS. Crystallization induces a second phase separation, i.e. the semicrystalline lamellar structure resulting from poly(oxyethylene)‐block crystallization is incommensurate with the oriented bcc structure, with which it coexists at low temperatures. However, crystallization produces an unoriented lamellar structure. WAXS indicates that the poly(oxyethylene) in the diblock copolymer crystallizes in its usual (helical) form.